---
kind: "section"
citation: "26 U.S.C. § 6204"
title: "26"
title_heading: "Internal Revenue Code"
number: "6204"
heading: "Supplemental assessments"
release: "119-102"
date: "2026-07-12"
url: "https://uscodex.org/usc/26/6204"
units:
  - "Subtitle F — Procedure and Administration"
  - "Chapter 63 — Assessment"
  - "Subchapter A — In General"
---

# §6204. Supplemental assessments

- (a) **General rule—** The [Secretary](/usc/26/7701.md?p=a-11-B) may, at any time within the period prescribed for assessment, make a supplemental assessment whenever it is ascertained that any assessment is imperfect or incomplete in any material respect.
- (b) **Restrictions on assessment—** For restrictions on assessment of [deficiencies](/usc/26/6211.md?p=a) in income, estate, gift, and certain excise taxes, see section 6213.

## Source credit

(Aug. 16, 1954, ch. 736, 68A Stat. 768; Pub. L. 93–406, title II, § 1016(a)(27), Sept. 2, 1974, 88 Stat. 932; Pub. L. 94–455, title XIX, § 1906(b)(13)(A), Oct. 4, 1976, 90 Stat. 1834.)

## Notes

### Editorial Notes

### Amendments

1976—Subsec. (a). Pub. L. 94–455 struck out “or his delegate” after “Secretary”.

1974—Subsec. (b). Pub. L. 93–406 substituted “gift, and certain excise taxes” for “and gift taxes”.

### Statutory Notes and Related Subsidiaries

### Effective Date of 1974 Amendment

Amendment by Pub. L. 93–406 applicable, except as otherwise provided in section 1017(c) through (i) of Pub. L. 93–406, for plan years beginning after Sept. 2, 1974, and, in the case of plans in existence on Jan. 1, 1974, amendment by Pub. L. 93–406 applicable for plan years beginning after Dec. 31, 1975, see section 1017 of Pub. L. 93–406, set out as an Effective Date; Transitional Rules note under section 410 of this title.